The present invention relates generally to the field of locking devices, and more particularly is directed to a locking system designed specifically to protect the fill pipes of underground flammable liquid storage tanks.
It is the common practice to store flammable liquids in underground storage tanks of either steel or fiberglass construction to provide for increased safety by minimizing the possibility of fire or explosion. In the usual automobile gasoline service station provided for the retail sale of gasoline, it is the present practice to store such flammables in relatively large size underground storage tanks, for example tanks of generally two thousand gallons to ten thousand gallons capacity or even more. Most gasoline service stations dispense three or more grades or products and such service stations usually include two or more separate islands or dispensing locations. Accordingly, multiple banks of such underground flammable liquid storage tanks are commonly in use throughout this and other countries.
Fill pipes lead from ground level to the underground storage tanks to facilitate easy filling of the tanks in well known manner. The fill pipes generally terminate at ground level in a known type of manhole or fill box construction and are equipped with conventional removable caps. Unless adequately protected by locking devices, these fill pipes could be easily accessible at ground level to unauthorized personnel. Considering then the present price of gasoline and the number of gallons of such product which are usually stored at a given service station location, it will be appreciated that the underground flammable liquid storage capacity represents a considerable investment to the service station owner or operator. Because of the ever increasing value of the underground stored flammable product, and the generally exposed and accessible location of most service stations, protective steps have been and must be taken to prevent and discourage the theft of gasoline during evening hours or during other periods when most service stations are closed and unattended.
In efforts to protect the service station owners and operators from major losses as a result of flammable liquid theft, prior workers in the art have designed and have utilized locking type caps for installation over the upper ends of the flammable liquid tank fill pipes to prevent tampering with the apparatus and to discourage unauthorized removal or theft of the stored liquid contents. While the presently available locking type fill caps have provided an increased degree of protection, it has been found that the devices that are currently available are prone to tampering and destruction by determined thieves. Because of the fact that most service stations close at night and that numerous service stations are located in relatively quiet areas where pedestrians would not ordinarily be expected to pass during late hours, would-be thieves usually have adequate time in which to pick, pry, or otherwise destroy the locks at the storage tank fill pipes to thereby gain entrance to the underground stored materials.
While of course, almost any type of lock can be broken if the thief possesses sufficient skill, the necessary tools, adequate determination and suitable time within which to do the job, the need remains to provide an extremely sturdy, simply designed and relatively inexpensive tank fill cap lockingif the thief possesses sufficient skill, the necessary tools, adequate determination and suitable time within which to do the job, the need remains to provide an extremely sturdy, simply designed and relatively inexpensive tank fill cap locking system which can offer the maximum deterrence to the efforts of a would-be gasoline thief.